Scroll saws are widely used by amateur and professional woodworkers to cut finely detailed fret work and other intricate patterns. Modern scroll saws utilize parallel arms to mount the saw blade. The parallel arms may be mounted to a common c-arm for pivoting about a single axis or they may be designed as completely separate upper and lower arms which pivot in tandem above vertically aligned pivot pins.
The extremely thin blades utilized with scroll saws are susceptible to breakage and accordingly must be mounted in such a manner that they can be easily replaced when necessary. It is essential to keep the scroll saw blade under proper uniform tension so as to preclude excessive tension or undue blade flexing, either of which can result in poor cutting action and premature blade failure. With either a parallel arm saw or a c-arm saw, the saw blade must be able to pivot slightly relative to the saw arms in order for the blade to be moved rapidly in a rectilinear path without breakage during the sawing operation. Accordingly, it is well-known in the art to construct a blade holder for a scroll saw which will accommodate limited pivotal movement between the blade holder and the saw arms which mount it.
One particular type of blade holding system which has proven to be particularly effective in scroll saws includes a round or tapered blade clamp that seats in a v-shaped groove in the lower arm of the saw in combination with a pair of upper clamp blocks which are pinned to the end of the upper saw arm. Blade removal is carried out by releasing the tension adjustment at the back of the arms and loosening the screw which clamps the blade between the upper clamp blocks, thus permitting the blade to be withdrawn from beneath the lower saw arm.
With the foregoing described blade holder arrangement, the v-shaped groove in the bottom arm against which the rounded lower blade holder engages, minimizes the surface area in contact and accordingly the frictional energy losses. As the lower blade holder wears, the surface area in contact between the holder and the lower arm v-groove increases thereby increasing the frictional energy losses upon movement of the blade. This adversely effects operation of the saw in two respects. First, the increased friction and attendant increase in energy losses attributable to the contact between the blade holder and the saw arm is undesirable and adversely effects saw performance. Second, since the wearing of the blade clamp is very gradual over time, the fact that the frictional resistance is continuously and gradually increasing causes the performance of the saw to likewise vary over time thus making it more difficult for an operator to adjust to the saw performance than would be the case if the change occurred all at once and remained constant thereafter.
It is therefore a primary object of the present invention to provide a blade holder for a scroll saw blade which by its unique design including the ability to continuously emit lubricant over the life of the blade holder greatly reduces the wear on the blade holder and accordingly the adverse effects associated with the increased frictional resistance between the blade holder and the saw arm.
Another objective of our invention is to provide a scroll saw blade holder wherein by reducing the wear on the blade holder the frictional resistance between the blade holder and the saw arm is maintained more constant than with prior art devices thereby making saw performance more uniform over the useful life of the blade holder.